Join Me in the Tub
by TC Stark
Summary: Smut one-shot between everyone's favorite narcissistic red doctor and my female OC. A stand alone story deriving from my trilogy. Rated M for some good interfacing.


TC Stark: So, I was bored at work and decided to make this little one-shot. It takes place during "Not Without You", but I thought it was too random to put in. For those who haven't read my stories, Rosie is a human girl who was acquired by Knock Out while he was a Con. He experimented on her and injected her with Energon. Eventually they came to have a deeper relationship and she convinces him to join the Autobots. In "The Other Side", Rosie is kidnapped by MECH and heavily experimented on – forcing Knock Out to repair her with cybernectics for her to live. Thus becoming a cyborg, which is a human with robot components who looks like a human. Don't worry KO hasn't become mushy, they have this almost curious scientists relationship now. Also, in my story "Mad World", he downloaded a mass displacement program that allowed him to scale down to around 6'4" to have fun time with his human.

Disclaimer: I only own Rosie.

"_Everything in the world is about sex except sex. Sex is about power."  
― __Oscar Wilde_

"Knock Out?"

Rosie had to admit that every time she left Knock Out at her house and came home to no reply, she was worried. MECH may have been destroyed and she made into a cyborg, but that didn't mean her human side wasn't slightly on edge. Living in a government paid for house and being associated with the Cybertronians could have left a target on her back, despite the Autobots experiencing peace during the months since her kidnapping.

Transforming her techno-organic arm into a blaster, the twenty-three-year-old snuck around the house with careful eyes. Though looking realistically human, they were in fact artificial. MECH had only removed one eye, but Knock Out explained that to only replace one would put her off balance. The rest of the team had been wary, not wanting her to turn into a science experiment; but she and the red doctor had been working towards new discoveries since the very beginning.

Scanning for any signs of body temperature or anything out of place, Rosie finally came upon the opened door of the bathroom and pushed it open. Immediately a smug Knock Out, looking quite proud of himself; stood with his hands on his hips, "Well, well, good to see you finally using the gifts I gave you."

Rosie let out a sigh of relief, as her arm transformed back to normal, "You scared me," She admitted, before quirking up an eyebrow, "What did you do?"

She of course was referring to the highly modified bathtub. In replacement of the normal sized one she usually had, there was a Jacuzzi style tub that looked truly too big for her bathroom. Shrugging, he simply put, "I was bored. _You _left me here with nothing to do, while you went shopping."

"You could have went back to the Autobot base."

"They're boring as well," Rosie rolled her eyes, as he insisted, "Besides, this is more fun."

Rosie knew the suggestiveness in his tone, placing her own hands on her hips and asking, "Are you saying you built me a large tub so we could be in it at the same time?"

Knock Out winked, "Right, beautiful. With my scaled down size I'll be able to comfortably join you for a bath."

"I haven't taken a bath since I was a kid," She laughed, "And won't you rust?"

Lightly scoffing, he explained, "How else would you clean a car except with soap and water? I would have to be submerged in water for a long time before I began to rust. There is always oil bathes, which I had installed at the base; but I doubt you would like them as much as I."

Rosie scrunched her nose, before looking over at the tub. It was inviting. There was water already filling the tub and she hadn't noticed before, but it was bubbling. Now, he really wasn't playing fair. Smirking to herself, her eyes turned seductive as she began pealing her clothes off. All the while Knock Out gazed at her.

A red plaid shirt and skinny jeans soon decorated the floor, Rosie standing in her plain bra and underwear. She challenged him with her eyes, Knock Out chuckling as he himself dipped into the tub. Though made out of metal alloy, his body was light and only caused the water to rise slightly without spilling over the side.

Knock Out's lustful red optics grazed over Rosie's lean figure, as his finger curled to beckon her, "Come, beautiful."

Their relationship had started less than favorably. Knock Out was a Con when he drove Rosie's boyfriend off the road and killed him mercilessly, taking her as a souvenir. She became his pet; his experiment. Electro prod, car battery cables, Energon shots – all to see the way her body reacted. And all the while reassuring her that she was part of something great and that _beauty was pain. _At that moment she understood his fetish for inter-species intercourse and gave in to the sex as some means of relief from the pain.

And then Breakdown was killed and Rosie was rescued by the Autobots. Megatron's and Starscream's callousness towards both incidents got under Knock Out's plating and it didn't take much convincing from her upon her return to him, to convince him the Autobots were the way to go. They joined and though tense at first, he fit in. They continued their sexual relationship, the female having become addicted to it.

Knock Out had reformed. Though he'd always be the vain doctor, he worked with Ratchet in making a better Synthetic Energon formula. Before the team had invaded Dark Mount he had made a promise to do right by her and make up for all the torture. She didn't care, as long as they kept fragging. And once the war was over, they had a better understanding of each other.

Rosie had started taking classes at the local community college. The relationship she had had with her deceased boyfriend had lasted six years and was one of immaturity. Because of him she had never gotten an education for herself pass high school. Knock Out encouraged her and she began becoming very interested in his scientific experiments. Under Ratchet's supervision, they continued with the Energon shots and she found herself becoming immune.

And then MECH kidnapped her. The Autobots had been so busy defeating Megatron and restoring their home world, while making peace with the humans; that they had forgotten about the terrorist group. Silas knew Team Prime had volunteered to stay on Earth and knew of the female human who had Energon flowing through her veins. She became a target an experiment, but in the harshest of ways.

The whole time there were no soothing words. No loving touches and no admiration for their work. They were not Knock Out. Instead they treated her like an object and did not care one bit. By the time the Cybertronians found her she had been missing an eye, had a mangled arm because they had tried to implant something, and a shaved head because they planned on slicing her open to see how her brain worked. She begged and pleaded that she was human and they laughed.

About six months had passed since that incident. Both eyes were turned into optics, her arm was replaced on the inside with bio-mechanics, and her hair was about shoulder length. Her previous brown unruly locks had gone down to the middle of her back, but she was happy she was simply alive. And that all Knock Out could call her was _beautiful, _even in her mangled state. It had made Jack change his opinion about the former Con, since beforehand all he held was hatred for him.

Rosie's body still looked human. As she took off her undergarments, Knock Out moaned at the lean figure, with peach colored skin, flat stomach, and average size breasts. He had memorized her body enough to know the cute round behind she had, itching to get his servos on her. What excited him the most was the metal through her nipples – she had no tattoos or any other piercings, those were just her guilty pleasures. And it reminded him of all the times he had hooked up a car battery and watched her vibrate from intensity. There were some deviant thoughts he couldn't control.

Slipping into the water, Rosie let out a coo at how nicely warm it was. They were on opposite ends of the tub, but even they could feel the heat from each from under the water line. Resting her head on the edge, she commented, "This is nice."

"Isn't it?" Knock Out purred, "I knew you would like it."

"I believe you're getting comfortable in my house."

Knock Out chuckled, "It's what the humans say _an old married couple._"

The statement made her think. Resting her hands on her stomach, Rosie asked, "What will happen? As I get older?"

"You're a cyborg, dear, you won't."

"What about my parents?"

"You will have to eventually tell them."

Rolling her eyes, she groaned, "Oh, joy. Yes, they will take that so well."

Knock Out chuckled, while positively stating, "Logically speaking, we probably won't have to say anything until you're thirty!"

Rosie snorted, "Not happening. We're going to have to say something beforehand. My grandma is Cuban, she's gonna want grandkids. I'll have to talk to Agent Fowler, he helped orchestrate Bumblebee meeting Raf's parents and his mother sounds pretty strict."

Though the Autobots had made peace with the American government and some of the USA's allies, they were still robots in disguise. Knock Out explained, "Well, Rosie, our kind doesn't reproduce like yours. We are not our own creators, the All Spark births us," Stopping to think, he suddenly became excited, "Or…it could be something different. We could take your DNA and my CNA and perhaps we could…" Trailing off, the doctor dropped his tone, "Babies are not supposed to be experiments, are they?"

Shaking her head, Rosie then crawled atop her lover and purred, "No, my dear."

"Hm, human femmes – you mention children and their hormones start spinning."

Leaning forward, she threatened, "My nails are sharper now, don't make me scratch your paint."

Smirking, Knock Out gripped her hips and pulled her down for her to notice his interfacing panel had already shifted aside, "Are you sure you want to play that game?"

Rosie smirked, while wrapping her arms around his neck and sliding her opening up and down the base of his spike, "More than sure."

The feel of her soft vulva lips touching his member caused a growl to emanate from Knock Out's throat, forcing him to bring the human female closer and pull her lips down to his. The red doctor was not a fan of his own species. Cybertronian femmes were boring to him and he was known for dabbling in inter-species erotica. He had found a true partner with this Rosie and ached every day to touch her soft flesh.

Feeling a burning in his loins, Knock Out smirked in Rosie's mouth. She had grown so much since she first landed within his palms. The human had been meek and timid to please her _lord, _but once they became equals she allowed her former personality to come to the surface and since being with him her confidence had sky rocketed.

Reaching over, Knock Out trailed the tip of his finger down in between her round aft cheeks and stuck a servo in her port. Rosie arched her back and groaned at the sensation of the sensitive nodes inside her being probed at. The red doctor smirked, as his appendix curled inward and watched the expressions crossing her face.

Rosie drug her nails down Knock Out's large shoulder struts, scratching the paint as she did so. He snarled, adding a finger as punishment while nipping at the nook of her neck, "Naughty."

"Cruel." Rosie breathed, positioning her opening at the tip of Knock Out's staff and pushing down.

Rosie's breath was instantly hitched in the back of her throat, squeezing her eyes shut as his staff hit every sensitive node inside her. Though the Cybertronians were made up of metal alloy, they weren't cold or uncomfortable feeling. Rather, his spike pulsed gently with energy as she felt him stretching her walls. Every time he entered her she was instantly hit with a wave of warm, throwing her head back and moaning.

Knock Out's hands gripped onto the back of her smooth thighs, rocking her atop his lap. Her legs were stretched as far as they could be, completely open for the doctor's length to push in as far as he could. Each buck tested as much as her cervix could be pushed in, the jabbing sending excitement and pain throughout her body.

With every thrust in, Rosie's body was bounced up. She gasped each time his tip hit her cervix and sighed every time he pulled away. The walls of her opening constricted when she ran up him and released when her hips pushed down. It was a constant symphony of tug and pull; catch and release. It was maddening and neither minded being lost within the chaos.

Latching his denta onto Rosie's nipple, Knock Out rolled the barbells around with his glossa, eliciting a throaty gasp from the human femme. The mech chuckled, "Your body reacts beautifully, my dear."

"Mm," Rosie hummed, eyes shut, "So does yours."

Rosie's hands roamed all along the plane of his chest, she leaned in and caught the cables of her neck with her mouth. A guttural growl escaped his own lips, as his grip on her hips tightened. She was displaying a dominating side to herself that only came out during interfacing. Her desires took over her and she almost became feral, attacking the crook of his neck aggressively.

Knock Out was no stranger to dishing out pain, but he enjoyed receiving it equally as much. Because of the Energon flowing through her veins and the operation to make her a cyborg, her teeth may have looked the same, but were sharper. So, they added a delicious pitch while sucking on his cables. Oh, how she knew how to rev his engines up – a sound that turned her on more than he knew.

As Knock Out's continuous stimulation of both valve and aft port continued, Rosie felt her body heating up. She was panting loudly, not caring if the neighbors heard her moan his name. Her bare chest pressed against his own; his pristine red shining brightly. The doctor kept up with the colors he was born with, wearing them proudly. Some mechs like Starscream and Megatron were born with a clean slate, no paint job; and he never understood why they didn't just add some color to their lives. He couldn't imagine just living being a dull grey.

Rosie's hand reached over and dug her nails into one of the tires on the back of him, causing him to grit his denta and pick up speed. Their grunts and groans were simultaneous, both bodies ebbing onto the peeking moments of orgasm. Knock Out's swollen spike had finally been pleasured to the brink of climax, shooting his fluid up into the human femme who soon quivered atop him – overtaken by her own finish.

Nails still latched onto the tire, Rosie desperately tried to catch her breath as Knock Out's systems shuddered. Slowly, his fingers slid from her aft port, though he stayed inside her valve. Finally, he hand slipped from the tire, slouching against his strong chest – completely exhausted from their little romp.

Fingers lacing through thick brunette hair, Knock Out closed his optic lids and smirked, "So, you like the tub?"

Smirking, Rosie could feel him harden within her once more as she moaned, "I love it."


End file.
